The present invention relates to motor vehicles and in particular to a method for controlling an intake system in engines with cylinder deactivation.
Methods for controlling various systems associated with cylinder deactivation have been previously disclosed. Caine et al. (U.S. patent number 2006/0196178) teaches an internal combustion engine with cylinder disablement and a method for controlling engine exhaust flow into an exhaust emission after-treatment device following cylinder disablement. The after-treatment device could be a catalytic converter, for example. The Caine design is intended to prevent fresh air from being pumped into the after-treatment device (catalytic converter) during a deactivated cylinder mode, which may prevent the after-treatment device from functioning properly.
Caine teaches an engine with a set of cylinders that may be deactivated. The exhaust from this deactivated set of cylinders may be reintroduced back into the intake stream, by way of a recirculation conduit, or the exhaust may travel through an exhaust conduit into an after treatment device, such as a catalytic converter. In the Caine design, a pair of butterfly valves controls the flow of exhaust into either the recirculation conduit or the exhaust conduit. When the cylinders are deactivated, the butterfly valves are configured to block exhaust from those deactivated cylinders from entering the exhaust conduit; and instead, send those uncombusted gases to a recirculation conduit, which then in turn, reintroduces those uncombusted gases to the air supply system.
Tadokoro et al. (U.S. Pat. No. 4,331,113) teaches a device for selective combustion in a multi-cylinder engine. Tadokoro teaches two intake passages that lead to two cylinders of an engine. The first intake passage includes a shutter valve that may open and close to control the flow of air through the first intake passage and into the first cylinder. In other words, Tadokoro teaches a shutter valve that closes to prevent combustible air from entering the first cylinder, thus providing a means for cylinder deactivation. Tadokoro does not teach the use of variable intake runner lengths, much less the concept of predefining prohibited operating ranges of a shutter valve associated with an intake runner to prevent noise, vibration and harshness.
The prior art has several shortcomings. There is no teaching in the prior art of controlling an intake system in conjunction with a multi-displacement engine having one or more cylinders that may be deactivated. There is a need in the art for a system and method that addresses the problems of the prior art.